A chronic memory disorder caused by severe deficiency of vitamin B1, thiamine, most commonly in people with alcohol dependence and malnutrition. It typically follows untreated Wernicke’s encephalopathy and is characterised by profound loss of the ability to form new memories, disorientation, and confabulation, in which the person unknowingly fills memory gaps with invented details. The underlying damage affects brain structures critical for memory. While prompt thiamine treatment can halt progression, established memory loss is often permanent. Prevention through adequate nutrition and thiamine supplementation in at-risk individuals is far more effective than treatment after the syndrome is established.